HS40 RUPP part 2

#1
It's winter in WI so what do you do? Blow snow and tear down your HS40 to investigate. Last summer with the help of OldMiniBikes members, you guided me thru and helped me to get my Rupp Roadster ticking again after 45 years, ie. HS40 RUPP post. The engine started and ran but had a few issues, so I thought I would open it up. First issue, valve clearance, intake .020. In the original build the end of the valve was TIG welded and ground down to get my .008, apparently it didn't hold up. I replaced it with a new /old valve and now have the correct clearance. My real concern is the dipper and the governor shaft have been mating in the crankcase. (see pic). WHAT the heck did I do wrong? In my original post, HS40 RUPP, I did have oil leaking from the governor shaft, the comments /concern were to check that I had the correct amount of oil and the crankcase breather was working correctly, that was verified. When ever I ran the engine I would get a little oil leaking from the governor shaft. Any of the above mentioned be a cause the oil escaping thru the G. shaft? Hope this makes sense. hs40dipper.jpg
 
#2
This happened to me on my first Hs50 build. Rod was contacting the governor shaft, same thing.
ended up bowing out of the Gomas race because it.
i removed the governor shaft and put a screw in the hole and everything is fine now
i replaced the damaged rod with a new one
 

markus

Well-Known Member
#3
Give the governor rod a circumcision if you are still using the rod as a pivot point for your throttle linkage, or just take it right out of the equation and plug the hole if you are using some other type of carburation. I snip them out of the way roaght on the 45 bend when the govenor gear and fly weights get removed usually in order to still utilize the stock throttle system since you need the pivot point.

If you are still using the governor shaft/rod for the throttle, it would be smart to pull it from the block and make sure the interference didn't cause any damage to the shaft or case.

Also, that thrust washer on your crankshaft needs to go!!!! That SHOULD NOT be in there on that type of engine. That's gonna cause some problems!!!

Have you done a full teardown and inspection? If your weld failed on a valve stem and there are things interfering, I would want to make sure I got all the debris out as well as make sure something didn't go into a journal or passage, up the cylinder wall etc..

Maybe when/if ARC makes another run of those Rods they could maybe do a batch with a reconfigured dipper for the HS like the ones that used be available that probably easier said than done though:
IMG_5309.JPG
 
#5
Give the governor rod a circumcision if you are still using the rod as a pivot point for your throttle linkage, or just take it right out of the equation and plug the hole if you are using some other type of carburation. I snip them out of the way roaght on the 45 bend when the govenor gear and fly weights get removed usually in order to still utilize the stock throttle system since you need the pivot point.

If you are still using the governor shaft/rod for the throttle, it would be smart to pull it from the block and make sure the interference didn't cause any damage to the shaft or case.

Also, that thrust washer on your crankshaft needs to go!!!! That SHOULD NOT be in there on that type of engine. That's gonna cause some problems!!!

Have you done a full teardown and inspection? If your weld failed on a valve stem and there are things interfering, I would want to make sure I got all the debris out as well as make sure something didn't go into a journal or passage, up the cylinder wall etc..

Maybe when/if ARC makes another run of those Rods they could maybe do a batch with a reconfigured dipper for the HS like the ones that used be available that probably easier said than done though:
View attachment 255924
Thanks @markus Welby MD, :) I'll do the circumcision. Did I date myself? I will do a tear down and inspect everything. The shim was in the 71 snow blower engine that I used the block, head and piston. Thought shim was used to take out end play on the crank. Thanks for the feedback.
 

markus

Well-Known Member
#6
Thanks @markus Welby MD, :) I'll do the circumcision. Did I date myself? I will do a tear down and inspect everything. The shim was in the 71 snow blower engine that I used the block, head and piston. Thought shim was used to take out end play on the crank. Thanks for the feedback.
Well, if you can remember watching that show so your getting pretty old, older than me at least :) Yea the shim/washer was for the HS bushing sidecover engines up to sometime in I think late 80's or 90's, then they phased it out by I guess changing a measurement somewhere or deciding that the case or crank could take the slamming back and forth alright without it (bushing engines have a lot of crank travel in them and really bounce during accel/decel). Yours is a ball bearing shaft, They are held captive to the bearing if installed properly. I'm surprised you actually got it in there without some sort of damage I would think that the screws that retain the bearing in place would have grabbed it and made a tighter fit trying to get the clip installed to the crank, coudl have got really ugly if that thing had got bent or wedged.
 

cfh

Well-Known Member
#7
you're running an Arc rod. take the damn governor completely out and throw it away. I tap the governor hole with 10-32 and put a 3/4" hex bolt in the hole. If you are running a stock carb (for god's sake WHY?) and need a pivot point, you can still do that. Just use a 1" long 10-32 hex head bolt and a nut. the old Tecumseh governor arm can be drill out slightly for that, and you and still use it as a pivot point on the new 10-32 bolt. I use the black hardened 10-32 hex head bolts.
 
#8
I'd like to keep the orig pivot point so I'll remove or cut it down. And yes I have the orig/stock carb, just keeping it original as it was when I bought it back in 1970...:)
 

cfh

Well-Known Member
#9
Why not go with a Dellorto? that way you can fully ditch the governor, and you'll gain essentially free performance with a slide carb. Dellortos were Rupp carbs. you don't need a ua19s either (expensive!) use a ua16 or ua18, they are easier to get and a lot less expensive.
 
#10
Why not go with a Dellorto? that way you can fully ditch the governor, and you'll gain essentially free performance with a slide carb. Dellortos were Rupp carbs. you don't need a ua19s either (expensive!) use a ua16 or ua18, they are easier to get and a lot less expensive.
I've seen alot of discussion on the slide carbs but never have pursued that option.
 

cfh

Well-Known Member
#11
if the motor stays on a Rupp, the dellorto idea is a good one. but they do cost more than the $20 china slide carb. however the intake manifold is readily available from Blackwiddow motor sports, unlike the china carb thing, where you have to make your own intake. dellortos don't really work better or worse either. but they do fit the era correctly. i mean you could order any model rupp from 1968 to 1975 with a dellorto. A dellorto looks quite BOSS too. they are cool Italian designs.
 
#12
Getting back to the project and inspecting further. I removed the connecting and piston. Pulled the cam. I never checked the ends on the cam when I did the original build, shame on me, the one end is fine, the end by the lobes is .007 under tolerance. Should I be concerned? Options? It is the original cam from the 70 rupp HS40.
 
#18
That's cool! A few years ago when my wife and I had our Roadster 2"s registered we would go to local car shows they were just as popular as the cars and we didn't enter them in the show.
 
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